Industry in general has been actively seeking a novel approach to partially or completely power vehicles using electricity stored in electrochemical cells. One problem which has been recognized by the automotive industry is the need to control the temperature of the electrochemical cells. The power generating capacity of an electrochemical cell is known to change with temperature, and electrochemical cells are known to fail when heated to high temperatures.
Various approaches to regulating the temperature of an electrochemical cell are described in U.S. Pat. No. 6,596,433 B2 (Godmundsson et al., issued Jul. 22, 2003), U.S. Pat. No. 5,817,434 (Brooker et al, issued Oct. 6, 1998), U.S. Pat. No. 5,449,571 (Longardner et al., issued Sep. 12, 1995), U.S. Pat. No. 6,797,427 B2 (Maleki et al., issued Aug. 9, 2001), and U.S. Pat. No. 6,942,944 B2 (Al-Hallaj et al., issued Sep. 13, 2005), each incorporated herein by reference in its entirety. Each of these approaches is inefficient in one or more aspects. For example, Godmundsson et al. (U.S. Pat. No. 6,596,433 B2) teaches a device including a compartment containing a phase change material that completely separates the electrochemical cells from a passage for flowing air. As such, the air stream cannot directly cool the electrochemical cell. Heat must first diffuse through the phase change material before it reaches the air stream. This arrangement is inefficient, particularly for dealing with applications that may require long times of high battery discharge power (such as during high speed driving or uphill driving of an automotive vehicle). Also Godmundsson does not teach a system for heating the electrochemical cells when the phase change material has cooled.
The basic idea is to be able to operate an electrochemical cell within a target temperature by providing heat when the temperature is below a minimum target temperature, removing heat when the temperature is above a maximum target temperature, and transferring heat into or out of a thermal energy storage material when the temperature of the electrochemical cell is within the target temperature range. To be a practical solution the approach to heating the electrochemical cell should employ a device that efficiently stores heat for extend periods of time (e.g., at least 4 or more hours) so that after the vehicle is parked in a cold environment the electrochemical cells can be rapidly heated to at temperature at which they can provide sufficient power to a an electric load, such as an electric motor.
There continues to exist a need for devices and systems for rapidly removing heat from an electrochemical cell, for rapidly providing heat to an electrochemical cell, for maintaining an electrochemical cell between a minimum target temperature and a maximum target temperature, to efficiently store heat, or any combination thereof. For example, there exists a need for a device that is capable of transferring heat from an electrochemical cell directly to both heat transfer fluids and thermal energy storage materials.